Objectives

• 1) What are the primary threats to freshwater ecosystems in the Lower Colorado River Basin, and how do they vary across spatial scales?
  
• 2) Which fishes are at greatest risk to anthropogenic and biotic threats?
  
• 3) What is the association between fish communities and specific threats indices different spatial scales?
  

Overview

Freshwater ecosystems of the western US deserts are among the most threatened in North America. Our project will develop and validate a suite of threat indicators for desert fishes using the Lower Colorado River Basin (LCRB) as a model system for future regional threat assessments. The analytical framework developed will be readily applicable to other regions and Fish Habitat Partnerships. We are conducting an investigation of the anthropogenic and biological factors threatening desert fishes within the LCRB to identify species, functional groups, and fish assemblages at most risk to imperilment, and provide a management tool to guide conservation strategies. Our project will partition the threat scores into different facets of anthropogenic and biological threats (e.g., hydrologic alteration, land use change, water quality, invasive species) to quantify the magnitude and variability of threats from different sources, and to identify the appropriate spatial scale and watersheds in most need of immediate management actions. This project will provide an adaptive framework to conduct regional risk assessments that could be utilized by other National Fish Habitat Partnerships through initial development of the threat assessment with stakeholder involvement, and continued refinement of the risk assessment as new information is collected.